Between the generator and the grid transformer which are interconnected by a set of busbars, such circuits include a generator circuit-breaker and switching apparatuses having two or three switching positions, which apparatuses are of the busbar switch and/or of the grounding switch type. Such a generator circuit can also be connected to a starter device via switch apparatus of this type.
Those various switch apparatuses are generally designed to be actuated automatically and electrically under the control of a control center. They must also be designed so as to be capable of being actuated manually by means of a handle in the event of an electricity failure, particularly a failure in the automatic control center. However, to ensure circuit element integrity, it is essential for manual actuation thereof to proceed in application of an accurately-specified procedure.
FIG. 6 is highly diagrammatic and shows an example of a generator circuit comprising a generator circuit-breaker FKG in series with a busbar switch SKG having two switching positions and connected between a generator 1 and a grid transformer 2, together with two grounding switches MALT1 and MALT2, each of which has two switching positions.
In FIG. 6, the generator circuit-breaker FKG and the busbar switch SKG are closed while the grounding switches MALT1 and MALT2 are open. The interlocking rules applicable to these various elements are common both to automatic actuation mode and to manual actuation mode and are as follows.
The busbar switch SKG must not be opened while the generator circuit-breaker FKG is closed. Neither of the grounding switches MALT1 and MALT2 must be closed while the busbar switch SKG is closed. The busbar switch SKG must not be closed while either of the grounding switches MALT1 and MALT2 is closed. The order of operations when actuating the busbar switch SKG and the grounding switches MALT1 and MALT2 starting from the configuration shown in FIG. 6 is as follows. Firstly the generator circuit-breaker FKG must be opened. Thereafter, the busbar switch must be opened, and only after that can each of the grounding switches be closed.
For safety reasons, it is therefore necessary to prevent those switch apparatuses being actuated manually in a manner that does not comply with the above order.